Surgical stapler with self-returning assembly

ABSTRACT

An articulating surgical tool includes a body portion and a tool assembly pivotally secured to the body portion by a mounting assembly. The mounting assembly includes at least a first spring member for maintaining a longitudinal axis of the tool assembly in alignment with a longitudinal axis of the body portion and for returning the longitudinal axis of the tool assembly into alignment with the longitudinal axis of the body portion following articulation of the tool assembly relative to the body portion.

This application claims the benefit of and priority to U.S. Provisional Patent Application Ser. No. 62/618,312 filed Jan. 17, 2018, the entire disclosure of which is incorporated by reference herein.

BACKGROUND Technical Field

The present disclosure relates to surgical staplers, and more particularly, to surgical staplers including a self-returning assembly for aligning, and/or maintaining alignment of, a tool assembly of the surgical stapler with an elongate body of the surgical stapler.

Background of Related Art

Minimally invasive approaches for thoracic and abdominal surgery have gained tremendous popularity over the past decade. The development of surgical stapling devices has enabled surgeons to perform stapling and sealing procedures with ease and minimal complications.

Endoscopic linear staplers include a tool assembly supported on a distal end of an elongate body which extends from a handle assembly. The tool assembly may be articulable relative to the elongate body to facilitate placement of the tool assembly within a body cavity of a patient. During insertion of the tool assembly into the body cavity of the patient, and prior to articulation of the tool assembly relative to the elongate body, it is desirable to maintain the tool assembly in alignment with the elongate body.

Accordingly, it would be beneficial to have a surgical stapler that incorporates an assembly for maintaining a tool assembly of the surgical stapler in, and/or returning the tool assembly to, alignment with an elongate body of the surgical stapler.

SUMMARY

A surgical tool including a self-returning assembly is disclosed. The surgical tool includes a body portion and a tool assembly pivotally secured to the body portion by a mounting assembly. The body portion includes proximal and distal ends and defines a longitudinal axis. The mounting assembly includes at least a first spring member for maintaining a longitudinal axis of the tool assembly in alignment with the longitudinal axis of the body portion and for returning the longitudinal axis of the tool assembly into alignment with the longitudinal axis of the body portion following articulation of the tool assembly relative to the body portion.

In embodiments the mounting assembly includes at least a first mounting member. The at least first mounting member is configured to pivotally connect the tool assembly to the body portion. The tool assembly may include a cartridge assembly and an anvil assembly. The at least first spring member may include first and second arms. The at least first mounting member may include a cam portion. The cam portion may be received between and engage the first and second arms.

In embodiments, articulation of the tool assembly in a first direction relative to the body portion causes the cam portion to deflect the first arm in a second direction. Similarly, articulation of the tool assembly in a third direction relative to the body portion causes the cam portion to deflect the second arm in a fourth direction. Deflection of the first and second arm may create a spring force against the cam portion. The at least first mounting member may include a pivot member and the at least first spring member includes an opening, wherein the pivot member is received within the opening.

The mounting assembly may include first and second spring members. In embodiments, first and second arms of the first spring member are parallel. Alternatively, the first and second arms of the first spring member angle towards one another. The at least first spring member may include a C-shaped flange for securing the first spring member to the body portion.

A surgical instrument is provide and includes a handle assembly and a surgical tool operably secured to the handle assembly. The surgical tool includes a body portion and a tool assembly pivotally secured to the body portion by a mounting assembly. The body portion includes proximal and distal ends and defines a longitudinal axis. The mounting assembly includes first and second spring members for pivotally supporting the tool assembly relative to the body portion. The first and second spring members return the tool assembly to an aligned position with the body portion from an articulated position relative to the body portion.

The mounting assembly may include first and second mounting members, with the first mounting member engaged with the first spring member and the second mounting member engaged with the second spring member. The first and second spring members may each include first and second arms and the first and second mounting members may each include a cam portion. The cam portion of the first mounting member may be received between and engage the first and second arms of the first spring member and the cam portion of the second mounting member may be received between and engage the first and second arms of the second spring member.

In embodiments, articulation of the tool assembly in a first direction relative to the body portion causes the cam portion of the first mounting member to deflect the first arm of the first spring member in a second direction and the cam portion of the second mounting member to deflect the first arm of the first spring member in the second direction. Deflection of the first arms of the first and second spring members may create a spring force against the cam portions of the respective first and second mounting members.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with a general description of the disclosure given above, and the detailed description of the embodiment(s) given below, serve to explain the principles of the disclosure, wherein:

FIG. 1 is a side, perspective view of an embodiment of the presently disclosed surgical stapling apparatus including a tool assembly with an anvil assembly and a cartridge assembly in an approximated position;

FIG. 2 is a side, perspective view of a disposable loading unit of the surgical stapling apparatus shown in FIG. 1 with the anvil assembly and cartridge assembly in an open position;

FIG. 3 is a side, perspective view of the loading unit shown in FIG. 2 with parts separated;

FIG. 4 is an enlarged side view of an elongate body portion and a mounting assembly of the loading unit shown in FIG. 2;

FIG. 5 is an enlarged side, perspective view of the elongate body portion and the mounting assembly shown in FIG. 4;

FIG. 6 is an enlarged view of the indicated area of detail shown in FIG. 5;

FIG. 7 is top, perspective view of a first mounting member of the mounting assembly shown in FIG. 4;

FIG. 8 is a bottom, perspective view of a second mounting member of the mounting assembly shown in FIG. 4;

FIG. 9 is a top view of a spring member of the mounting assembly shown in FIG. 4;

FIG. 9A is a top view of a spring member of a mounting assembly according to another embodiment of the present disclosure;

FIG. 10 is a top, perspective view of the spring member shown in FIG. 9;

FIG. 11 is a top view of a first housing half of the elongate body portion of the loading unit shown in FIG. 4;

FIG. 12 is a top view of a second housing half of the elongate body portion of the loading unit shown in FIG. 4;

FIG. 13 is an enlarge view of the indicated area of detail shown in FIGS. 11 and 12;

FIG. 14 is a top view of the mounting assembly shown in FIG. 4; and

FIG. 15 is a bottom view of the mounting assembly shown in FIG. 4.

DETAILED DESCRIPTION

Embodiments of the present disclosure will now be described in detail with reference to the drawings wherein like reference numerals designate identical or corresponding elements in each of the several views. In this description, the term “proximal” is generally used to refer to the portion of the apparatus that is closer to a clinician, while the term “distal” is generally used to refer to the portion of the apparatus that is farther from the clinician.

As noted above, alignment of a tool assembly of a surgical stapler with an elongate body of the surgical stapler facilitates insertion and removal of the tool assembly into/from within the body cavity of a patient directly through an incision or with the aid of a cannula or other access device. Alignment of the tool assembly with the elongate body also provides a user with a reference for the location of the tool assembly relative to the elongate body prior to articulation of the tool assembly. To ensure that the tool assembly of the surgical stapler is maintained in alignment with the elongate body of the surgical stapler during insertion and removal of the tool assembly into/from within the body cavity of a patient, and to facilitate return of the tool assembly into alignment with the elongate body following articulation of the tool assembly, the embodiments of the present disclosure include a self-returning mounting assembly.

Although the embodiments of the present disclosure will be described as they relate to linear endoscopic and laparoscopic surgical staplers, it is envisioned that the aspects of the present disclosure may be incorporated into surgical instruments of various configurations having an articulating tool assembly, e.g., curved surgical staplers, vessel sealers, graspers, cutters, retractors, etc.

FIG. 1 illustrates an embodiment of the presently disclosed surgical instrument shown generally as surgical stapler 10. The surgical stapler 10 includes a handle assembly 12, an adapter assembly 14 releasably secured to the handle assembly 12, and a loading unit 100 releasable secured to the adapter assembly 14. The handle assembly 12 and the adapter assembly 14 are configured to effect operation of the loading unit 100. The loading unit 100 may be configured for single use, e.g., disposable, and multiple uses, e.g., including a replaceable cartridge. Although the handle assembly 12 is shown as being powered, and with a pistol grip, it is envisioned that the handle assembly may be manually operated, and/or may have alternative configurations, e.g. pencil grip.

In embodiments, the adapter assembly 14 of the surgical stapler 10 may be integrally formed with the handle assembly 12 and/or integrally formed with the loading unit 100. For a detailed description of the structure and function of an exemplary powered handle and adapter assemblies, please refer to commonly owned U.S. Pat. No. 9,055,943 (“the '943 patent”), the content of which is incorporated by reference herein in its entirety. For a detailed description of an exemplary manual handle assembly, please refer to commonly owned U.S. Pat. No. 8,070,033, the content of which is incorporated by reference herein in its entirety.

Referring to FIGS. 1 and 2, the loading unit 100, for use with the surgical stapler 10, includes a body portion 102 and a tool assembly 104 pivotally secured to the body portion 102. The loading unit 100, including the body portion 102 and the tool assembly 104, will only be described to the extent necessary to fully disclose the aspects of the present disclosure. For a detailed description of the structure and function of exemplary loading units, please refer to commonly owned U.S. Pat. App. Pub. Nos. 2013/0098965, 2016/0249921, and 2016/0249929 (“the '965 Publication”, “the '921 Publication”, and “the '929 Publication”, respectively), and commonly owned U.S. patent application Ser. No. 15/440,010 (“the '010 application”), the contents of each of which are hereby incorporated by reference herein in their entirety.

With particular reference now to FIG. 3, the body portion 102 of the loading unit 100 includes a first housing half 110 a and a second housing half 110 b which are contained within an outer sleeve 112 of the body portion 102. A drive member 122 of a drive assembly 120 is slidably received within a channel (not shown) defined by the first and second housing halves 110 a, 110 b. An articulation link 118 extends through the body portion 102 of the loading unit 100 and facilitates articulation of the tool assembly 104 relative to the body portion 102. A pair of blow-out plate assemblies 120 a, 120 b is positioned adjacent the distal end of the first and second housing halves 110 a, 110 b to prevent outward buckling and/or bulging of the drive member 122 of the drive assembly 120 during articulation of the tool assembly 104 and during firing of the loading unit 100. The distal end of the drive member 122 of the drive assembly 120 supports a clamping member 124. In embodiments, the drive member 122 is formed from a plurality of stacked sheets 122 a-d of material, e.g., stainless steel. A detailed description of the above-identified components of the loading unit 100 is provided in the '965 and '921 Publications, the content of which was previously incorporated herein by reference.

Still referring to FIG. 3, the tool assembly 104 of the loading unit 100 includes an anvil assembly 130 and a cartridge assembly 140 which are movable in relation to each other between an open position (FIG. 2) and an approximated position (FIG. 1). The anvil assembly 130 includes an anvil body 132 and an anvil plate 134. The cartridge assembly 140 includes a support plate 142, a cartridge body 144, a plurality of staples “S”, and a staple firing assembly 150 that includes an actuation sled 152 and a plurality of staple pushers 154. The cartridge assembly 140 is receivable in a jaw member 146. As noted above, the loading unit 100 may be configured such that the cartridge assembly 140 is replaceable to permit reuse of the loading unit 100. Alternatively, the loading unit 100 may be configured for single use. The jaw member 146 of the tool assembly 104 is pivotally secured to the anvil body 132 of the anvil assembly 130. For a detailed discussion of an exemplary tool assembly, see the '965 Publication which has been incorporated herein by reference.

In embodiments configured for use with a powered handle assembly 12 (FIG. 1), the loading unit 100 may include an identification assembly (not shown) for communicating with the handle assembly 20 (FIG. 1). In embodiments, the loading unit 100 may include one or more lockout features (not shown) for preventing the firing, and/or subsequent firing, of the surgical stapler 10, e.g. shipping lock, lockout mechanism, shipping wedge. In embodiments, the staples “S” of the tool assembly 104 may be of any size, configuration, and/or formed of any material.

With reference now to FIGS. 4-6, the tool assembly 104 (FIG. 2) of the loading unit 100 is pivotally secured to body portion 102 of the loading unit 100 by a mounting assembly 200. The mounting assembly 200 includes a first mounting member 210, and a second mounting member 220 secured to the first mounting member 210. The mounting assembly 200 further includes a self-returning assembly in the form of first and second spring members 230, 240 operably secured to the first and second housing halves 110 a, 110 b, respectively, of the body assembly 102 and pivotally secured to the first and second mounting members 210, 220, respectively. The mounting assembly 200 is configured to maintain the tool assembly 104 in longitudinal alignment with the tool assembly 104 during passive use of the tool assembly 104, i.e., during insertion and withdrawn of the tool assembly into a patient, and to facilitate return of the tool assembly 104 into alignment with the body portion 102 from an articulated position relative to the body portion 102.

As noted above, the tool assembly 104 of the loading unit 100 (FIG. 2) is articulated relative to the body portion 102 of the loading unit 100 by the articulation link 118 (FIG. 3). It is envisioned that the aspects of the present disclosure may be modified for use with other articulation mechanism, e.g., cable actuated, gear driven, passive.

With particular reference now to FIG. 7, the first mounting member 210 of the mounting assembly 200 (FIG. 4) of the loading unit 100 (FIG. 4) includes a base portion 212, a pivot member 214 extending radially outward from the base portion 212, and a cam portion 216 of the first mounting member 210 extending outwardly from the base portion 212. The base portion 212 is configured to enable pivoting of the first mounting member 210 relative to the first housing half 110 a. When the loading unit 100 is assembled, the pivot member 214 of the first mounting member 210 extends perpendicular to a longitudinal axis “X” of the loading unit 100. The pivot member 214 is configured to engage the first spring member 230 (FIG. 9). More particularly, the pivot member 214 of the first mounting member 210 is configured to be received through an opening 231 (FIG. 9) in the first spring member 230. The pivot member 214 is further configured to be received through an opening 131 (FIG. 3) in the anvil body 132 (FIG. 3) of the anvil assembly 130 (FIG. 3). As will be described below in relation to a pivot member 224 of the second mounting member 220, the pivot member 214 of the first mounting member 210 may include a tab (not shown) for securing the first spring member 230 to the first mounting member 210.

As noted above, the cam portion 216 of the first mounting member 210 extends outwardly from the base portion 212. The cam portion 216 of the first mounting member 210 extends parallel to the longitudinal axis “X” (FIG. 4) of the loading unit 100 (FIG. 4) and is configured to be received between and engage spring arms 238 a, 238 b of the first spring member 230. The body portion 212 of the first mounting member 210 includes a cutout 211 to accommodate the pivot portion 234 of the first spring member 230, and to permit pivoting of the first mounting member 210 relative to the first spring member 230.

With reference now to FIG. 8, the second mounting member 220 of the mounting assembly 200 (FIG. 4) of the loading unit 100 (FIG. 4) includes a base portion 222, a pivot member 224 extending laterally outward from the base portion 222, a cam portion 226 extending longitudinally outwardly from the base portion 222, and a connector portion 228 extending longitudinally outwardly opposite the cam portion 226. Although shown including a pair of pins 222 a (FIG. 3) for securing the second mounting member 220 to the first mounting member 210, it is envisioned that the first and second mounting members 210, 220 may be secured together in any suitable manner. The base portion 222 is configured to enable pivoting of the second mounting member 220 relative to the second housing half 110 b.

With reference to FIG. 8, the pivot member 224 of the second mounting member 220 of the mounting assembly 200 is configured to engage the second spring member 240 (FIG. 9). More particularly, the pivot member 224 is configured to be received through an opening 241 of the of the second spring member 240. As shown, the pivot member 224 includes a tab 224 a that is configured to secure the second spring member 240 to the second mounting member 220. For a detailed description of an exemplary pivoting connection, please refer to the '010 application, the content of which was previously incorporated herein by reference.

As noted above, the cam portion 226 of the second mounting member 220 of the mounting assembly 200 extends outwardly from the base portion 222. When the loading unit 100 is assembled, the cam portion 226 of the first mounting member 220 extends parallel to the longitudinal axis “X” (FIG. 4) of the loading unit 100 (FIG. 4). The cam portion 226 of the second mounting member 220 is configured to be received between and engage spring arms 246 a, 246 b of the second spring member 240. The body portion 222 of the second mounting member 220 includes a cutout 221 to accommodate a pivot portion 244 of the second spring member 240, and to permit pivoting of the second mounting member 220 relative to the second spring member 240.

The connector portion 228 of the second mounting member 220 of the mounting assembly 200 is configured to engage and support the tool assembly 104 (FIG. 2) of the loading unit 100 (FIG. 2). More particularly, the connector portion 228 of the second mounting member 220 defines openings 229 for receiving pivot pins 133 (FIG. 3). The pivot pins 133 pivotally secure together the anvil body 132 of the anvil assembly 130 and the jaw member 146 (FIG. 3) of the cartridge assembly 140 (FIG. 3). The connector portion 228 of the second mounting member 220 further defines a slot 225 for receiving the drive member 122 (FIG. 3) of the drive assembly 120 (FIG. 3) therethrough.

With reference now to FIGS. 9 and 10, the first and second spring members 230, 240 are substantially similar. The first and second spring members 230, 240 each include a base portion 232, 242, a pivot portion 234, 244 secured to a first end of the base portion 232, 242, a C-shaped flange 236, 246 secured to the second end of the base portion 232, 242, and first and second spring arms 238 a, 248 a, 238 b, 248 b extending from the C-shaped flange 236, 246, respectively, along the respective base portion 232, 242. As shown, the base portions 232, 242, the pivot portions 234, 244, the C-shaped flanges 236, 246, and the first and second spring arms 238 a, 238 b, 248 a, 248 b are integrally formed, e.g., monolithic. In embodiments, the integrally formed first and second spring members 230, 240 may be formed from a single sheet of material. Alternatively, any or all of the spring members 230, 240 may be formed of separate components that are secured together, e.g., welded, adhesive. The spring members 230, 240 may be formed of metal, plastic, or other suitable semi-flexible material.

With continued reference to FIGS. 9 and 10, the base portion 232, 242 of each of the first and second spring members 230, 240 includes an elongate body. The base portions 232, 242 may each include a tab 232 a, 242 b, respectively, that engages the outer sleeve 112 (FIG. 3) of the body portion 102 (FIG. 3) of the loading unit 100 (FIG. 3). As discussed above, the pivot portion 234, 244 of the first and second spring members 230, 240 each define an opening 231, 241, respectively, configured to receive the respective pivot members 214, 224 of the respective first and second mounting members 210, 220. As shown and described, the pivot portion 244 of the second spring member 240 defines a notch 241 a in communication with the opening 241 in the pivot portion 244 for accommodating a tab 224 a of the pivot portion 224 of the second mounting member 220. As noted above, the first mounting member 210 and the first spring member 230 may also be configured in a similar manner.

The C-shaped flanges 236, 246 of the respective first and second spring members 230, 240 of the mounting assembly 200 are disposed on the second end of the respective base portions 232, 242. The C-shaped flanges 236, 246 are configured to facilitate securement of the respective first and second spring members 230, 240 to the first and second housing halves 110 a, 110 b, respectively, of the body portion 102. As noted above, the C-shaped flanges 236, 246 support the first and second spring arms 238 a, 248 a, 238 b, 248 b, respectively.

With particular reference to FIG. 9, the first and second spring arms 238 a, 248 a, 238 b, 248 b, extend parallel to one another. As will be described in further detail below, free ends the first and second spring arms 239 a, 249 a, 239 b, 249 b of the respective first and second spring members 230, 240 engage the respective cam portion 216, 226 of the first and second mounting members 210, 220.

With reference to FIG. 9A, in another embodiment of a spring member, the first and second spring arms 238 a′, 238 b′ of a spring member 230′ are supported on a C-shaped flange 236′ such that the first and second spring arms 238 a′, 238 b′ of the spring member 230′ extend at an angle towards one another. More particular, free ends 239 a′, 239 b′ of the respective first and second arms 238 a′, 238 b′ of the spring member 230′ extend towards one another. The first and second spring arms 238 a′, 238 b′ of the spring member 230′ are configured to deflect away from each other in order to receive cam portion 216 of the first mounting member 210 therebetween. As will be described in further detail below, the spring loaded nature of the engagement between the spring member 230′ and the first mounting member 210 requires a larger force to articulate the tool assembly 104 relative to the body portion 102. Although shown and described with reference to the first mounting member 210, the spring member 230′ may be used with the second mounting member 220.

With reference now to FIGS. 11-13, the first and second housing halves 110 a, 110 b of the body portion 102 of the loading unit 100 are configured to support respective first and second spring members 230, 240. Distal portions 111 a, 111 b of the first and second housing halves 110 a, 110 b each define a plurality of channels 250, 252, 254 for accommodating the respective first and second spring members 230, 240. Each of the distal portions 111 a, 111 b of the first and second housing halves 110 a, 110 b are curved to accommodate articulation of the tool assembly 104 of the loading unit 100 relative to the body portion 102 of the loading unit 100.

With particular reference to FIG. 13, the distal portions 111 a, 111 b of the first and second housing halves 110 a, 110 b, respectively, are substantially similar. Each distal portion 111 a, 111 b includes a central slot or channel 250, a first channel 252 disposed on a first side of the central channel 250, and a second channel 254 disposed on an opposite side of the central channel 250. Each of the first and second channels 252, 254 are mirror images of one another. The central channel 250 is configured to receive the body portion 232, 242 of the first and second spring members 230, 240. The first channel 252 is configured to receive the first arms 238 a, 248 a of the first and second spring members 230, 240, respectively, and the second channel 254 is configured to receive the second arms 238 b, 248 b of the first and second spring members 230, 240, respectively.

With continued reference to FIG. 13, the first and second channels 252, 254 are defined by an inner surface 253 a, 255 a, respectively, and an outer surface 253 b, 255 b, respectively, of the first and second housing halves 110 a, 110 b. The inner surfaces 253 a, 255 a extend parallel to one another and to the longitudinal axis “X” (FIG. 4) of the body portion 102 (FIG. 4) of the loading unit 100 (FIG. 4). The inner surfaces 253 a, 255 a are configured to engage the first and second arms 238 a, 248 a, 238 b, 248 b of the first and second spring members 230, 240, respectively, when the first and second arms 238 a, 248 a, 238 b, 248 b of the first and second arms 230, 240, respectively, are in a first or relaxed position. More particularly, the spacing between the inner surfaces 253 a, 255 a of the first and second housing halves 110 a, 110 b, respectively, correspond to the width of the cam portions 216, 226 (FIGS. 7 and 8) of the first and second mounting members 210, 220, respectively.

The outer surfaces 253 b, 255 b of the first and second housing halves 110 a, 110 b extend at an angle relative to inner surfaces 253 a, 255 a, respectively, to form substantially triangular first and second channels 252, 254. The triangular configuration of the first and second channels 252, 254 created by the outer surfaces 253 b, 255 b of the first and second housing halves 110 a, 110 b enables the first and second arms 238 a, 248 a, 238 b, 248 b of the respective first and second spring members 230, 240 to deflect during articulation of the tool assembly 104 relative to the body portion 102 of the loading unit 100.

With reference now to FIGS. 14 and 15, the first spring member 230 of the mounting assembly 200 is supported between the first housing half 110 a of the body portion 102 of the loading unit 100 and the first mounting member 210 of the mounting assembly 200. Similarly, the second spring member 240 of the mounting assembly 200 is supported between the second housing half 110 b of the body portion 102 of the loading unit and the second mounting member 220. The cam portions 216, 226 of the respective first and second mounting members 210, 220 are received between the first and second spring arms 238 a, 248 a, 238 b, 248 b, respectively, of the respective first and second spring members 230, 240 such that the free ends 239 a, 249 a, 239 b, 249 b of the respective first and second spring arms 238 a, 248 a, 238 b, 248 b engage the respective cam portion 216, 226.

With continued reference to FIGS. 14 and 15, during operation of surgical stapler 10 (FIG. 1), the tool assembly 104 of the loading unit 100 may be articulated relative to the body portion 102 of the loading unit 100 through operation of the handle assembly 12 (FIG. 1) and/or adapter assembly 14 (FIG. 1). As the tool assembly 104 pivots in a first direction, as indicated by arrows “A” in FIGS. 14 and 15, the cam portions 216, 226 of the respective first and second mounting members 210, 220, engage the free ends 239 a, 249 a, respectively, of the respective first spring arms 238 a, 248 a of the first and second spring members 230, 240, respectively, and deflect the first spring arms 238 a, 248 a outwardly, as indicated by arrows “B” in FIGS. 14 and 15. The outward deflection of the second spring arms 238 a, 248 a creates a biasing force in the first spring arms 238 a, 248 a that, when the force causing the articulation of the tool assembly 104 is removed, causes the tool assembly 104 to return to its initial position.

Similarly, as the tool assembly 104 pivots in a second direction, as indicated by arrows “C” in FIGS. 14 and 15, the cam portions 216, 226 of the respective first and second mounting members 210, 220, engage the free ends 239 b, 249 b, respectively, of the respective second spring arms 238 b, 248 b of the first and second spring members 230, 240, respectively, and deflect the second spring arms 238 b, 248 b outwardly, as indicated by arrows “D” in FIGS. 14 and 15. The outward deflection of the second spring arms 238 b, 248 a creates a biasing force in the second spring arms 238 b, 248 b that, when the force causing the articulation of the tool assembly 104 is removed, causes the tool assembly 104 to return to its initial position.

As noted above, the first and second arms 238 a, 248 a, 238 b, 248 b of the respective first and second spring members 230, 240 may be angled inwardly to create a biasing force against the cam portions 216, 226 of the respective first and second mounting members 210, 220 prior to any articulation of the tool assembly 104 relative to the body portion 102 of the loading unit 100. As such, the first and second arms 238 a, 248 a, 238 b, 248 b of the respective first and second spring members 230, 240 are preloaded. In this manner, a greater force would be required to articulate the tool assembly 104 as the spring bias provided by the first and second spring arms 238 a, 248 a, 238 b, 248 b of the respective first and second spring members 230, 240 on the respective cam portions 216, 226 of the first and second mounting members 210, 220 must be overcome before the tool assembly 104 may articulate. The preloading of the first and second spring arms 238 a, 248 a, 238 b, 248 b of the respective first and second spring members 230, 240 limits incidental and/or accidental articulation of the tool assembly 104 relative to the body portion 102 during use of the surgical stapler 10. Similarly, the preloaded configuration maintains the tool assembly 104 in alignment with the body portion 102 to facilitate insertion and/or removal of the loading unit 100 from within a patient, e.g., through an access port.

Persons skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments. It is envisioned that the elements and features illustrated or described in connection with one exemplary embodiment may be combined with the elements and features of another without departing from the scope of the present disclosure. As well, one skilled in the art will appreciate further features and advantages of the disclosure based on the above-described embodiments. Accordingly, the disclosure is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. 

What is claimed is:
 1. A surgical tool comprising: a body portion having proximal and distal ends and defining a longitudinal axis; a tool assembly pivotally secured to the body portion by a mounting assembly, wherein the mounting assembly includes at least a first spring member for maintaining a longitudinal axis of the tool assembly in alignment with the longitudinal axis of the body portion and for returning the longitudinal axis of the tool assembly into alignment with the longitudinal axis of the body portion following articulation of the tool assembly relative to the body portion; and an articulation assembly for pivoting the tool assembly relative to the body portion between aligned and articulated positions.
 2. The surgical tool of claim 1, wherein the mounting assembly includes at least a first mounting member, the at least first mounting member being configured to pivotally connect the tool assembly to the body portion.
 3. The surgical tool of claim 2, wherein the at least first spring member includes first and second arms and the at least first mounting member includes a cam portion, the cam portion being received between and engaging the first and second arms.
 4. The surgical tool of claim 3, wherein articulation of the tool assembly in a first direction relative to the body portion causes the cam portion to deflect the first arm in a second direction.
 5. The surgical tool of claim 4, wherein articulation of the tool assembly in the second direction relative to the body portion causes the cam portion to deflect the second arm in the first direction.
 6. The surgical tool of claim 5, wherein deflection of the first and second arm creates a spring force against the cam portion.
 7. The surgical tool of claim 2, wherein the at least first mounting member includes a pivot member and the at least first spring member includes an opening, wherein the pivot member is received within the opening.
 8. The surgical tool of claim 3, wherein the first and second arms of the at least first spring member are parallel.
 9. The surgical tool of claim 3, wherein the first and second arms of the at least first spring member angle towards one another.
 10. The surgical tool of claim 1, wherein the tool assembly includes a cartridge assembly and an anvil assembly.
 11. The surgical tool of claim 1, wherein the mounting assembly includes first and second spring members.
 12. The surgical tool of claim 1, wherein the at least first spring member includes a C-shaped flange for securing the at least first spring member to the body portion.
 13. A surgical instrument comprising: a handle assembly; and a surgical tool operably secured to the handle assembly, the surgical tool including: a body portion having proximal and distal ends and defining a longitudinal axis; a tool assembly pivotally secured to the body portion by a mounting assembly; and an articulation assembly for pivoting the tool assembly relative to the body portion between an aligned position in alignment with the body portion and articulated position out of alignment with the body portion, the mounting assembly includes first and second spring members for pivotally supporting the tool assembly relative to the body portion, wherein the first and second spring members return the tool assembly to the aligned position with the body portion from the articulated position relative to the body portion.
 14. The surgical instrument of claim 13, wherein the mounting assembly further includes first and second mounting members, the first mounting member being engaged with the first spring member and the second mounting member being engaged with the second spring member.
 15. The surgical instrument of claim 14, wherein the first and second spring members each include first and second arms and the first and second mounting members each include a cam portion, the cam portion of the first mounting member being received between and engaging the first and second arms of the first spring member and the cam portion of the second mounting member being received between and engaging the first and second arms of the second spring member.
 16. The surgical instrument of claim 15, wherein articulation of the tool assembly in a first direction relative to the body portion causes the cam portion of the first mounting member to deflect the first arm of the first spring member in a second direction and the cam portion of the second mounting member to deflect the first arm of the first spring member in the second direction.
 17. The surgical instrument of claim 16, wherein deflection of the first arms of the first and second spring members creates a spring force against the cam portions of the respective first and second mounting members.
 18. A surgical tool comprising: a body portion having proximal and distal ends and defining a longitudinal axis; and a tool assembly pivotally secured to the body portion by a mounting assembly, wherein the mounting assembly includes at least a first spring member for maintaining a longitudinal axis of the tool assembly in alignment with the longitudinal axis of the body portion and for returning the longitudinal axis of the tool assembly into alignment with the longitudinal axis of the body portion following articulation of the tool assembly relative to the body portion, the at least first spring member including first and second arms.
 19. The surgical tool of claim 18, wherein the at least first mounting member includes a cam portion, the cam portion being received between and engaging the first and second arms.
 20. The surgical tool of claim 19, wherein articulation of the tool assembly in a first direction relative to the body portion causes the cam portion to deflect the first arm in a second direction and articulation of the tool assembly in the second direction relative to the body portion causes the cam portion to deflect the second arm in the first direction. 